Subsurface Bioreactors as a Possible Addition to Enhance WW Treatment Plant Operation: A Brief Review

Abstract

Prior to the establishment of the United Sates Environmental Protection Agency and the Clean Water Act signed into law in 1972, water treatment was done on a minimal level or was not present at all. Since then, scientists strive to improve and advance new and existing water treatment processes that water can be discharged safely into water bodies. Constructed wetlands as engineered waste water treatment systems are used today as a final waste water treatment before the treated waste water is released into a water body. Surface flow and sub terranean flow constructed wetland options exist and are used for the treatment of municipal, agricultural and industrial waste water containing pollutants such as human waste, soap, fats, chemicals, and pharmaceutical compounds. They can be operated all year round (24/7) at temperatures that might exceed 35°C (95°F) and as low as around -26°C (-15°F). Constructed wetland systems in general depend on the quality of pretreatment for the inflow waste water, the hydrology and the carrier material as well as the climate, the vegetation and the physical and technical properties of the plant-based sewage treatment plants themselves, as well as the operational principle applied to the constructed wetland system. Constructed wetland operated as surface and or sub terranean flow mode can be a cost-effective and low-energy consuming alternative that requires only minimal operational effort. Experience shows that sub-terranean flow surface constructed wetland can be a long-term cost-effective solution that operates stable in various hot and cold weather conditions for decades with minimal operational and maintenance effort.